Most json packages dictate a data structure that corresponds to json values.
To serialize other values to json, then that value must be marshalled into
the specified structure.

This library avoids this marshalling step, and is thus potentially more
efficient when serializing arbitrary data structures. Unfortunately
json-builder cannot yet read or process json data, and it's not clear
to me yet how pull a similar kind of trick to avoid unnecessary data
structures when parsing json data into arbitrary data types.